Cowl flap control for aircraft



Feb. 27, 1951 LAWRENCE 2,543,112

COWL FLAP CONTROL FOR AIRCRAFT Filed July 5, 1946 2 Sheets$heet l IN VEN TOR.

[ya/m0 M. LHWRENL'E BY M -ATTOR NEY Feb. 27, 1951 D. M. LAWRENCE 2,543,112

COWL FLAP CONTROL FOR AIRCRAFT Filed July 5, 1946 2 Sheets-Sheet 2 I N VEN TOR.

DUN/7L0 M. LHWHENL'E BY 5 Val -ATTORNEY- Patented Feb. 27, 1951 2,543,112 cowL FLAP CONTROL Foa AIRCRAFT Donald M. Lawrence, Wood-Ridge, N. J assignor to Bendix Aviation Corporation, Teterboro. v N. J a corporation of Delaware Application July 5, 1946. Serial No. 681,621

2 Claims.

My invention relates to control systems and devices and more particularly to an improved means for automatically operating fluid flow-control flaps which form part of the cowling of an aircraft engine, or for a ventilating duct or the like.

An object of my invention is to provide means responsive to the temperature of the engine and the cooling fluid medium for difierentially actuating the fluid flow flaps in accordance therewith.

Another object of my invention is to provide means responsive to variation in temperature of the cooling medium for automatically opening the flow fiaps upon an increase in temperature and closing the flow flaps upon a decrease in the temperature of the cooling medium.

Another object of my invention is to provide means responsive to the temperature of the aircraft engine and the temperature of a fluid cooling medium for varying the adjustment of a control means for said cooling medium.

Another object of my invention is to provide a novel floating lever arrangement having a control means operably connected thereto and a first temperature responsive means and a second temperature responsive means connected to said lever in such a manner that the control means may be difierentially operated thereby.

Another object of my invention is to provide a novel system for controlling the cooling of an aircraft engine, including a first control means responsive to the temperature of the engine and a second control means responsive to the temperature of a cooling medium, and both of said control means simultaneously controlling the fiow of the cooling medium.

Another object of my invention is to provide in combination a first means reacting relatively slowly to temperature change within the engine and a second means reacting relatively rapidly to temperature change within the engine cowling,

both of said means arranged for jointly effecting the adjustment of the now of a cooling medium within said cowling.

Another object of my invention is to provide novel means for effecting a relatively stable automatic co'wl flap control for an aircraft, wherein the hunting periods of the control will be relatively infinitesimal.

Another object of my invention is to provide a novel cowl fiap control combining a first means responsive directly to the engine cylinder temperature, and a second means responsive to the temperature of the cooling medium for the engine so 'as to provide in effect means for anticipating change in engine temperature due to change in ly in matters of shape. size, and arrangement of parts within the principle of the invention to the full extent indicated by the broad and general meanings of the terms in which the appended claims are expressed.

In the drawings:

Figure 1 is a diagrammatic sectional view of one form of the invention.

Figure 2 is a diagrammatic sectional view of a second form of the invention.

Referring to the drawing of Figure 1, there is shown an aircraft engine whose temperature it is desired to control indicated at I. The engine I is shown as an internal combustion engine of the radial cylinder air cooled type having the usual propeller 2 and engine cylinders 3. The engine cylinders 3 are mounted in the conventional man ner within the nacelle skin. The engine proper is surrounded by an annular cowling 4 having an air inlet 5 at the forward or leading edge thereof. The cowling 4 is provided with a series of air outlet openings one of which is shown at 6, extending longitudinally of the cowling 4. Each opening 6 is provided with a shutter I pivotally connected at 8 to the cowling 4. The shutter 1 may completely close its respective opening 6 as well as uncover the said opening 6 in diiferent degrees.

The shutter I is shown diagrammatically as pivotally connected at 9A to one end of an actuating link 9 which has the opposite end thereof pivotally connected at 93 to a piston rod l0, which projects through an opening IIIA formed in a casing IOB. The piston rod I0 is controlled by a piston l l longitudinally movable within a cylinder l2 mounted within the casing IIIB. The piston H divides the cylinder 12 into chambers l3 and M.

The chambers l3 and I4 are connected respectively by pipes l5 and It to a valve chamber ll formed in a control valve It. The valve chamber I! is closed at opposite ends by the sealing members "A and "B.

Pipes l9 and 20 lead from opposite ends of the valve chamber I1 and are connected by a pipe 2| to a pipe connector 21A of a suitable type, which projects through the casing MB. The connector HA is connected by a pipe 2|B to a supply or storage tank 22 for a suitable fluid medium such as oil, whereby fluid medium may be returned under pressure from said valve chamber H to the storage tank 22.

A pipe 23 leads from the storage tank 22 to a gear pump 24 driven by a suitable power means so as to draw said fluid medium from the tank 22 through the pipe 23 into the gear pump 24. An outlet pipe 25 leads from the gear pump 24 and conducts the fluid medium under pressure of the gear pump 24 to a pipe connector 25A which also projects through the casing IOB. The pipe connector 25A is in turn connected within the casing IDB to the valve chamber ll of the control valve I 8 at a point intermediate the openings to the pipes 15 and It. A valve stem 21 is longitudinally adjustable in the valve chamber l1 and has provided the valve members 21A and 21B fixedly mounted on the valve stem 21 for controlling the openings to the pipes l5 and 16, respectively.

In Figure 1, the valve stem 21 is. shown as adjusted so that the valve members 21A and 21B close the openings to the pipes l5 and I6, respectively. However, upon the longitudinal adjustment of the valve stem 21 from the position shown, toward the end member "A, it will be readily seen that the pipes l5 and IE will be opened by the valve members 21A and 2113, respectively, and fluid medium under the force of the gear pump 24 will be drawn from the supply tank 22, through pipe 23 to gear pump 24 and forced under pressure from the gear pump 24 through pipe 25, connector 25A, pipe 26, valve chamber I1, pipe 15 to chamber l3, biasing the piston ll so as to adjust the shutter 1 in a counterclockwise direction for opening the outlet 6. Such adjustment of the piston H further causes fluid medium within chamber I4 to pass through pipe it into valve chamber l1 and return to the.

supply tank 22 through pipe is, pipe 2|, connector 2IA and pipe 213.

Moreover, upon longitudinal adjustment of the valve stem 26 from the position shown, toward the end member B, it will be readily seen that fluid medium under pressure of the gear pump 24 will enter the chamber 14 biasing the piston I I in a direction for causing the closing of the air outlet 6.

In order to automatically control the operation of the valve I8, I have provided a floating lever 29 pivotally connected at one end 30 to the valve stem 21. The opposite end of the floating lever 29 is pivotally connected at 3| to an actuating rod 32. The actuating rod 32 is pivotally connected at 33 to an expansible bellows 34 mounted within the casing I013. The interior of the bellows 34 is connected by a pipe 34A to a pipe connector 343 which projects through the casing wall )3. The connector 343 is connected by a pipe 35A to a bulb 35 which is mounted within and adjacent the cylinder 3. The bulb 35, pipe 35A, connector 34B, pipe 34A and interior of bellows 34 contains a suitable fluid medium of a type well known in the art and expansible upon a rise in temperature at the cylinder block so as to expand the bellows 34, and cause the contraction of the bellows 34 upon a decrease in the temperature of the cylinder block 3. Thus a rise in the engine cylinder temperature will cause the lever 29 to move in a clockwise direction about a point 36 positioned intermediate the opposite ends of the lever 29 while a decrease in the temperature of the engine cylinder 3, will cause the floating lever 3| to move in a counterclockwise direction about the point 36.

Pivotally connected at the point 36 is an actuating rod 31. The actuating rod 31 projects through an opening iUC formed in the casing 10B and is pivotally connected at 38 to a bimetallic strip 39 which in turn is fixedly mounted at an end 40 to a block 4! aflixed at the outer side of the casing IOB. The bimetallic strip 39 is spaced apart from the outer surface of the casing IOB so as to readily respond to change in temperature of the airstream flowing in to the cowling 4 from the inlet 5 and out at the outlet 6, as distinguished from the engine cylinder 3. The bimetallic strip 39 is so arranged as to flex in a clockwise direction about the fixed end 40 upon an increase in the temperature 01' the airstream.

Further, the strip 33 flexes in a counterclockwise direction about the fixed point 40 upon a decrease in the temperature of the airstream.

The said airstream is arranged to enter the cowling 4 through the forward air inlet I so as to flow across the engine cylinder 3, and then across the bimetallic strip 33 spaced apart from the engine cylinder as shown, whereby the bimetallic element 39 may indicate change in the temperature of the cooling medium as distinguished from the engine temperature. Change in the temperature of the engine is indicated by the temperature responsive bulb 35. As shown, the airstream passes from the bimetallic element 32 out the engine cowl through the-outlet 8. The supply of such fluid air medium may or course be controlled by varying the size or the opening I by the adjustment or the shutter I. The casing IOB may be conveniently mounted within the cowling 4 by brackets or other suitable supporting means and a guard 42 may surround the bimetallic element 39 so as to protect the same from the force of the fluid medium.

In the operation or the foregoing control system, it will be seen that movement of the flap 1 will immediately efiect the volume or mass of air flowing through the cowling 4. Moreover, for any short period or time, conditions bein equal, the heat dissipated from the cylinder 3 will be constant. However, a change in the mass flow of air through the cowling 4 and across the engine I will cause an immediate reaction in the air stream temperature. The bimetallic strip 33 will react rapidly to change in temperature of the air stream due to the low inertia of the air and rapidity with which change in air temperature may be effected. However, change at the engine cylinder due to change in the mass flow of air will be relatively slow, due to the inertia and greater mass at the engine cylinder, so that the temperature responsive bulb 35 will be relatively slow to respond to change in the temperature of the cooling mas or airstream.

It will be readily seen that if the flaps I were controlled merely from the temperature of the engine relatively long periods of hunting would result due to the extremes at which the flaps would be adjusted so as, for example, to efiect,

first a .rise in temperature, and thena decrease in temperature, so that the engine might approach the desired optimum temperature. While, it the flaps were adjusted merely in response to the temperature of the cooling medium by the bimetallic member 39, for example, there would be no true indication as to the temperature of the engine, since the temperature of the cooling medium or air flow might well vary due'to natural causes not reflecting the temperature or the engine.

By combining the two temperature responsive means 35 and 39 in the manner indicated, however, the bimetallic member 33 tends to react to change in temperature of the cooling medium more rapidly than the bulb 35 and thus tends to reset or move the flap towards the position of stability, so as to prevent the extreme adjustments of the flap I which would otherwise result, if the same were solely under the control or the bulb 35.

A second form of the invention is shown in Figure 2 in which like numerals indicate corresponding parts to those shown in Figure 1. In the arrangement of Figure 2, the bellows 34 is connected by rod 32 at 3| to an adjustable arm 50. The arm 50 is pivotally connected at "A to an adjustment member 5|. The pivot 50A is slidably mounted in a suitable slot 503 formed in the adjustment member 5|.

The member 5| is pivotally mounted at 52 and has a pointer 53 through which the same may be manually adjusted so as to vary the temperature setting of the regulator by varying the position of the pivot 50A.

The opposite end of the arm 50 is pivotally connected at 54 through a suitable linkage to one end of a floating lever 55. The opposite end of the floating lever 55 is pivotally connected by a suitable linkage 56 to a point intermediate the opposite ends of a floating lever 51. The floating lever 55 is connected at a point 58 intermediate its opposite ends to the control valve 21.

One end of the floatin lever 51 is connected by a rod 59 to an expansible bellows 69 mounted within the casing 1013. The interior of the bellows 59 is connected by a pipe connector 60A which projects through the casing Wall MB to a pipe 61. The pipe 6! leads to a temperature responsive bulb 62 which is mounted within thecowling 3 and adjacent the opening 5 in spaced relation to the engine cylinder 3 so as to respond to the temperature of the airstream flowing in the cowling 5 from the inlet 5 and out at the outlet 6, as distinguished from the engine cylinder 3.

The bulb .52. pipe BI and interior of the bellows 60 contains a suitable fluid medium of a type well known in the art and expansible upon a rise in the temperature of the airstream so as to expand bellows 60, while the bellows 60 contracts upon a decrease in the temperature of the airstream so as to effect a corresponding adjustment of the control valve 21.

The opposite end of the lever 51 is pivotally connected at 63 to the piston rod It! so that upon adjustment of the control valve 21 in response to change in temperature of the airstream the resulting adjustment of the piston I I effects through the lever 51, link 56 and lever 55 a follow up or resetting adjustment of the control valve 21 to the neutral position.

The operation of the form of the invention shown in Figure 2 will be readily apparent from the previous description of Figure 1. It will be readily seen, however, from the foregoing that in the form of the control shown in'Figure 2, there is provided novel means for controlling the temperature of the engine I including means for adjusting the temperature setting, the member 53. and means for resetting the control in response to movement of the flap 1 that is the linkage arrangement 51.

Although only two embodiments of the invention have been illustrated and described, various changes in the form and relative arrangements of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claims for a definltion of the limits of the invention.

What is claimed is:

1. A cooling system for an aircraft engine of the type including a cowling surrounding said engine, said cowling having provided an air inlet and an air outlet whereby a stream of air may flow through said cowling for cooling said engine. a shutter located at the air outlet for controlling the rate of flow of said airstream, and first means responsive to the temperature of said engine for adjusting said shutter so as to vary the rate of flow of said airstream so as to maintain a redetermined engine temperature; the improvement comprising second means positioned in said airstream at a point adjacent said shutter and responsive'only to change in the temperature of' the airstream so as to anticipate change in engine temperature due to change in the airstream temperature, third means operated by said first and second means whereby said shutter may be simultaneously adjusted thereby for controlling the rate of flow of said airstream, and fourth manually adjustable means to vary the response of said first and second means to the temperature of the engine and airstream, respectively.

2. For use in an aircraft having a combustion engine, a cowling surrounding said engine having an air inlet and an air outlet whereby a stream of air may flow through said cowling for cooling said engine, and a shutter at said air outlet for controlling the rate of flow of said airstream, whereby said engine temperature may be maintained at a predetermined temperature, a regulator for the adjustment of said shutter comprising a first temperature responsive means having a sensing element 'mounted adjacent said engine and responsive to changes in engine temperature, said first temperature responsive means being operated by said sensing element in response to changes in engine temperature, a second temperature responsive means having a sensing element positioned within said airstream, said sensing element being responsive to changes in the airstream temperature, said second temperature responsive means being operated by its sensing element in response to changes in the airstream temperature, a fluid pressure motor for adjusting said shutter, a valve for controlling the operation of said motor, a floating lever pivotally connected to said valve, pivotal connections between said first and second temperature responsive means and said floating lever whereby said valve is actuated by the operation of the first and second temperature responsive means in response to their respective sensing elements to thereby operate said fluid motor to adjust said shutter, a pivotal connection between said fluid motor and floating lever for imparting a followup action to said valve upon movement of said motor, and manually adjustable lever means pivotally connected to said floating lever to vary the response of said first and second temperature res sponsive means to the temperature of the engine and airstream, respectively.

DONALD M. LAWRENCE.

REFERENCES crrnn The following references are of record in the .file of this patent:

UNITED STATES PATENTS Number Name Date 1,376,462 Robertshaw May 3, 1921 2,081,762 Nissen May 25, 1937 2,101,369 Jorgensen Dec. 7, 1937 2,168,599 Beisel Aug. 8, 1939 2,255,639 Annin Sept. 9, 1941 2,268,083 Rapuano Dec. 30, 1941 2,341,789 Justus Feb. 15, 1944 2,432,186 Whann Dec. 9, 1947 FOREIGN PATENTS Number Country Date 943,017 Great Britain Jan. 28, 1931 697,925 Germany Oct. 26, 1940 

